diff --git a/api/src/main/java/org/cardanofoundation/rosetta/api/block/model/entity/ProtocolParams.java b/api/src/main/java/org/cardanofoundation/rosetta/api/block/model/entity/ProtocolParams.java
index 779d94180..bd6c375a3 100644
--- a/api/src/main/java/org/cardanofoundation/rosetta/api/block/model/entity/ProtocolParams.java
+++ b/api/src/main/java/org/cardanofoundation/rosetta/api/block/model/entity/ProtocolParams.java
@@ -94,17 +94,18 @@ public static ProtocolParams fromJSONObject(JSONObject shelleyJsonObject) {
     p.setMaxBlockSize(shelleyProtocolParams.getInt("maxBlockBodySize"));
     p.setMaxTxSize(shelleyProtocolParams.getInt("maxTxSize"));
     p.setMaxBlockHeaderSize(shelleyProtocolParams.getInt("maxBlockHeaderSize"));
-    p.setKeyDeposit(shelleyProtocolParams.getBigInteger("keyDeposit"));
-    p.setPoolDeposit(shelleyProtocolParams.getBigInteger("poolDeposit"));
+    p.setKeyDeposit(BigInteger.valueOf(shelleyProtocolParams.getLong("keyDeposit")));
+    p.setPoolDeposit(BigInteger.valueOf(shelleyProtocolParams.getLong("poolDeposit")));
     p.setNOpt(shelleyProtocolParams.getInt("nOpt"));
-    p.setDecentralisationParam(shelleyProtocolParams.getBigDecimal("decentralisationParam"));
+    p.setDecentralisationParam(
+        BigDecimal.valueOf(shelleyProtocolParams.getLong("decentralisationParam")));
     p.setExtraEntropy(shelleyProtocolParams.getJSONObject("extraEntropy").getString("tag"));
     JSONObject protolVersion = shelleyProtocolParams.getJSONObject("protocolVersion");
     p.setProtocolMajorVer(protolVersion.getInt("major"));
     p.setProtocolMinorVer(protolVersion.getInt("minor"));
-    p.setMinUtxo(shelleyProtocolParams.getBigInteger("minUTxOValue"));
-    p.setMinPoolCost(shelleyProtocolParams.getBigInteger("minPoolCost"));
-    p.setAdaPerUtxoByte(shelleyProtocolParams.getBigInteger("minFeeA"));
+    p.setMinUtxo(BigInteger.valueOf(shelleyProtocolParams.getLong("minUTxOValue")));
+    p.setMinPoolCost(BigInteger.valueOf(shelleyProtocolParams.getLong("minPoolCost")));
+    p.setAdaPerUtxoByte(BigInteger.valueOf(shelleyProtocolParams.getLong("minFeeA")));
 
     return p;
   }
diff --git a/api/src/main/java/org/cardanofoundation/rosetta/api/construction/service/impl/ConstructionApiServiceImpl.java b/api/src/main/java/org/cardanofoundation/rosetta/api/construction/service/impl/ConstructionApiServiceImpl.java
index d8a15a741..f05be8c47 100644
--- a/api/src/main/java/org/cardanofoundation/rosetta/api/construction/service/impl/ConstructionApiServiceImpl.java
+++ b/api/src/main/java/org/cardanofoundation/rosetta/api/construction/service/impl/ConstructionApiServiceImpl.java
@@ -73,13 +73,21 @@ public ConstructionPreprocessResponse constructionPreprocessService(
       ConstructionPreprocessRequest constructionPreprocessRequest) {
 
     NetworkIdentifier networkIdentifier = constructionPreprocessRequest.getNetworkIdentifier();
-    ConstructionPreprocessMetadata metadata = constructionPreprocessRequest.getMetadata();
+    Optional<ConstructionPreprocessMetadata> metadata = Optional.ofNullable(
+        constructionPreprocessRequest.getMetadata());
+    Double relativeTtl;
+    DepositParameters depositParameters;
+    if(metadata.isPresent()) {
+      relativeTtl = cardanoService.checkOrReturnDefaultTtl(metadata.get().getRelativeTtl());
+      depositParameters = Optional.ofNullable(metadata.get().getDepositParameters()).orElse(cardanoService.getDepositParameters());
+    } else {
+      relativeTtl = Constants.DEFAULT_RELATIVE_TTL;
+      depositParameters = cardanoService.getDepositParameters();
+    }
 
-    Double relativeTtl = cardanoService.checkOrReturnDefaultTtl(metadata.getRelativeTtl());
     Double transactionSize = cardanoService.calculateTxSize(
         NetworkIdentifierType.findByName(networkIdentifier.getNetwork()),
-        constructionPreprocessRequest.getOperations(), 0,
-        metadata.getDepositParameters());
+        constructionPreprocessRequest.getOperations(), 0, depositParameters);
     Map<String, Double> response = Map.of(Constants.RELATIVE_TTL, relativeTtl,
         Constants.TRANSACTION_SIZE,
         transactionSize);
@@ -110,40 +118,36 @@ public ConstructionMetadataResponse constructionMetadataService(
   @Override
   public ConstructionPayloadsResponse constructionPayloadsService(
       ConstructionPayloadsRequest constructionPayloadsRequest) {
-    int ttl = constructionPayloadsRequest.getMetadata().getTtl();
+
     List<Operation> operations = constructionPayloadsRequest.getOperations();
 
     checkOperationsHaveIdentifier(operations);
 
     NetworkIdentifierType networkIdentifier = NetworkIdentifierType.findByName(constructionPayloadsRequest.getNetworkIdentifier().getNetwork());
     log.info(operations + "[constuctionPayloads] Operations about to be processed");
-
-    ProtocolParameters protocolParameters = constructionPayloadsRequest.getMetadata()
-        .getProtocolParameters();
-    String keyDeposit;
-    String poolDeposit;
-    // TODO need to convert OpenAPI ProcotolParameters to domain ProtocolParams. Then merge with the one from indexer/config
-    if(protocolParameters != null) {
-      keyDeposit = protocolParameters.getKeyDeposit();
-      poolDeposit = protocolParameters.getPoolDeposit();
+    Optional<ConstructionPayloadsRequestMetadata> metadata = Optional.ofNullable(
+        constructionPayloadsRequest.getMetadata());
+    int ttl;
+    DepositParameters depositParameters;
+    if(metadata.isPresent()) {
+      ttl = cardanoService.checkOrReturnDefaultTtl(metadata.get().getTtl()).intValue();
+      depositParameters = Optional.ofNullable(metadata.get().getProtocolParameters()).map(protocolParameters -> new DepositParameters(protocolParameters.getKeyDeposit(), protocolParameters.getPoolDeposit())).orElse(cardanoService.getDepositParameters());
     } else {
-      ProtocolParams protocolParametersFromIndexerAndConfig = ledgerService.findProtocolParametersFromIndexerAndConfig();
-      keyDeposit = protocolParametersFromIndexerAndConfig.getKeyDeposit().toString();
-      poolDeposit = protocolParametersFromIndexerAndConfig.getPoolDeposit().toString();
+      ttl = Constants.DEFAULT_RELATIVE_TTL.intValue();
+      depositParameters = cardanoService.getDepositParameters();
     }
 
-    UnsignedTransaction unsignedTransaction = null;
+    UnsignedTransaction unsignedTransaction;
     try {
       unsignedTransaction = cardanoService.createUnsignedTransaction(
           networkIdentifier, operations, ttl,
-          new DepositParameters(keyDeposit,
-              poolDeposit));
+          depositParameters);
     } catch (IOException | CborSerializationException | AddressExcepion | CborException e) {
       throw ExceptionFactory.cantCreateUnsignedTransactionFromBytes();
     }
     List<SigningPayload> payloads = cardanoService.constructPayloadsForTransactionBody(
         unsignedTransaction.hash(), unsignedTransaction.addresses());
-    String unsignedTransactionString = null;
+    String unsignedTransactionString;
     try {
       unsignedTransactionString = CborEncodeUtil.encodeExtraData(
           unsignedTransaction.bytes(),
diff --git a/api/src/main/java/org/cardanofoundation/rosetta/common/services/CardanoService.java b/api/src/main/java/org/cardanofoundation/rosetta/common/services/CardanoService.java
index 039836758..619c20e6c 100644
--- a/api/src/main/java/org/cardanofoundation/rosetta/common/services/CardanoService.java
+++ b/api/src/main/java/org/cardanofoundation/rosetta/common/services/CardanoService.java
@@ -62,4 +62,5 @@ ProcessOperations convertRosettaOperations(NetworkIdentifierType networkIdentifi
   UnsignedTransaction createUnsignedTransaction(NetworkIdentifierType networkIdentifier, List<Operation> operations, int ttl, DepositParameters depositParameters) throws IOException, CborSerializationException, AddressExcepion, CborException;
 
   String submitTransaction(String signedTransaction);
+  DepositParameters getDepositParameters();
 }
diff --git a/api/src/main/java/org/cardanofoundation/rosetta/common/services/impl/CardanoServiceImpl.java b/api/src/main/java/org/cardanofoundation/rosetta/common/services/impl/CardanoServiceImpl.java
index da8d45b71..e845d264a 100644
--- a/api/src/main/java/org/cardanofoundation/rosetta/common/services/impl/CardanoServiceImpl.java
+++ b/api/src/main/java/org/cardanofoundation/rosetta/common/services/impl/CardanoServiceImpl.java
@@ -509,4 +509,15 @@ public String submitTransaction(String signedTransaction) throws ApiException {
         }
     }
 
+  /**
+   * Returns the deposit parameters for the network fetched from the protocolparameters
+   * @return Depositparameters including key- and pooldeposit
+   */
+  @Override
+    public DepositParameters getDepositParameters() {
+      ProtocolParams protocolParametersFromIndexerAndConfig = ledgerDataProviderService.findProtocolParametersFromIndexerAndConfig();
+      return new DepositParameters(protocolParametersFromIndexerAndConfig.getKeyDeposit().toString(),
+            protocolParametersFromIndexerAndConfig.getPoolDeposit().toString());
+    }
+
 }
diff --git a/api/src/main/resources/rosetta-specifications-1.4.15/api.json b/api/src/main/resources/rosetta-specifications-1.4.15/api.json
index 365b3520a..a6403a093 100644
--- a/api/src/main/resources/rosetta-specifications-1.4.15/api.json
+++ b/api/src/main/resources/rosetta-specifications-1.4.15/api.json
@@ -1988,8 +1988,7 @@
         "type": "object",
         "required": [
           "network_identifier",
-          "operations",
-          "metadata"
+          "operations"
         ],
         "properties": {
           "network_identifier": {
diff --git a/api/src/main/resources/rosetta-specifications-1.4.15/api.yaml b/api/src/main/resources/rosetta-specifications-1.4.15/api.yaml
index f9f50c103..91a95fe4a 100644
--- a/api/src/main/resources/rosetta-specifications-1.4.15/api.yaml
+++ b/api/src/main/resources/rosetta-specifications-1.4.15/api.yaml
@@ -1342,7 +1342,6 @@ components:
       required:
         - network_identifier
         - operations
-        - metadata
       properties:
         network_identifier:
           $ref: '#/components/schemas/NetworkIdentifier'